In their simplest form, voice communications systems route a voice communication to a destination based upon an identifier that is associated with the destination. As an example, telephone networks commonly route telephone calls to a destination based on a telephone number that is associated with the destination.
Call forwarding systems have long been used to route telephone calls to a destination other than the one specified by the party who initiated the telephone call. In a typical implementation, a user could program a call forwarding system to route calls received by the user's office telephone to a telephone at the user's home.
It has become commonplace for a single person to use multiple communications devices that are each associated with a different telephone number or other identifier. As a consequence, usage of call forwarding systems has increased, and the manner in which call forwarding systems are used has become more complex. For instance, a single user may be reachable at numbers corresponding to a telephone at their home, a telephone at their place of employment, a mobile or non-mobile computer acting as a telephone using software that implements voice over internet protocol technologies, one or more mobile telephones that the user carries on the user's person, and/or one or more telephones that are integrated into the onboard communication systems of an automobile. For some users, the effort that must be expended to manage a call forwarding system could present a barrier to adoption of the system.